Salbutamol is a fast-relief medicine used to open the airways in asthma and COPD (bronchodilator). The inhaler is used when symptoms occur (shortness of breath, chest tightness, wheezing) or before exercise to prevent bronchospasm. It is generally well tolerated.
Also known as: albuterol, Ventolin, Asthalin
DailyMed/FDA (NIH/NLM) — approved Salbutamol inhaler (MDI/HFA) label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=583c6408-45cc-9121-e063-6294a90afcc4
DailyMed label (MDI/HFA): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=583c6408-45cc-9121-e063-6294a90afcc4 — pharmacokinetics: PubMed PMID 3653233 (Pharmacokinetics and absolute bioavailability of salbutamol, 1987); PMID 1457264 (Determination of the relative bioavailability of salbutamol, 1992)
Combining theophylline with salbutamol has additive effects (tremor, tachycardia, hypokalaemia).
Salbutamol (beta2-agonist) and theophylline both raise cAMP — the former by direct beta2 receptor activation, the latter by phosphodiesterase inhibition — and the pharmacodynamic effect is additive. Theophylline "increases release of endogenous catecholamines" and the label links this to an "increased risk of ventricular arrhythmias"; salbutamol "may produce significant hypokalaemia... with the potential to produce adverse cardiovascular effects". The combination is common in practice (severe asthma/COPD), but high doses of both add up tachycardia, tremor, nausea and potassium loss, with arrhythmia risk mainly in elderly or cardiac patients. Use the lowest effective doses, monitor serum potassium and symptoms (palpitations, tremor, anxiety) and reduce theophylline if toxicity signs appear.
Salbutamol + theophylline: additive beta-adrenergic stimulation — tachycardia, tremor, hypokalaemia and arrhythmia risk. Monitor potassium and cardiovascular symptoms.
Both drugs stimulate adenylate cyclase / raise cAMP and may potentiate the β2 effect and potassium loss.
Monitor tremor, palpitations and check potassium in at-risk patients.
Symptomatic hypokalaemia, arrhythmias.
Monitor serum potassium and heart rhythm, especially in patients with cardiovascular disease.
DailyMed (FDA) — approved Theophylline label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5e64036a-ee3e-42e7-9e59-881f88a4e298 ; approved Salbutamol label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3236f82c-14e9-dfd4-e063-6294a90ac43d — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Salbutamol + magnesium: additive hypokalaemia (the β2-agonist lowers potassium).
β2-agonists such as salbutamol activate the Na⁺/K⁺-ATPase pump and promote intracellular potassium uptake, causing transient hypokalaemia. Magnesium sulfate can also lower serum potassium and, at high concentrations, depresses neuromuscular and cardiac conduction. Together (a common situation in severe acute asthma, where both are used), hypokalaemia can be more pronounced and increase the risk of arrhythmias, especially in patients with cardiovascular disease or on digoxin. Serum potassium and ECG should be monitored during magnesium infusion in patients receiving high-dose β2-agonists, correcting hypokalaemia if needed.
Salbutamol + magnesium: additive hypokalaemia (the β2-agonist lowers potassium). Monitor serum potassium and ECG.
β2-agonists cause K+ shift into cells; combined with magnesium, hypokalaemia may be accentuated, especially at high doses.
Serum potassium.
Weakness, cramps, arrhythmias.
Monitor potassium at high doses or with prolonged use.
DailyMed (FDA) — approved Salbutamol label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3236f82c-14e9-dfd4-e063-6294a90ac43d ; approved Magnesium sulfate label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a5a9f565-639c-4b22-b9e5-718bac7cfcf3 — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Non-selective beta-blockers such as sotalol antagonise the bronchodilator effect of salbutamol and may trigger bronchospasm.
Sotalol is a non-selective beta-blocker that also prolongs the QT interval (class III); it blocks bronchial beta2 receptors, directly opposing the bronchodilator effect of salbutamol, and the sotalol label warns that "uncorrected hypokalaemia or hypomagnesaemia can exaggerate the degree of QT prolongation, and increase the potential for Torsade de Pointes", recommending correction before initiation. Salbutamol, like other beta2-agonists, "may produce significant hypokalaemia in some patients, possibly through intracellular shunting, with the potential to produce adverse cardiovascular effects" (salbutamol label). The combination therefore adds bronchial antagonism to the arrhythmogenic risk (hypokalaemia + QT). Avoid whenever possible in patients with asthma and cardiovascular disease; if unavoidable, use the lowest salbutamol dose, correct potassium/magnesium and monitor ECG and respiratory function.
Salbutamol + sotalol: sotalol (non-selective beta-blocker) opposes the bronchodilator effect of salbutamol, and beta2-agonist-induced hypokalaemia may exaggerate sotalol QT prolongation. Avoid or monitor ECG and potassium.
Sotalol blocks bronchial β2 receptors, opposing salbutamol.
Monitor respiratory function and response to the bronchodilator.
Bronchospasm, worsening dyspnoea.
Avoid non-selective beta-blockers in asthmatic patients; if unavoidable, use cardioselective agents with caution.
DailyMed (FDA) — approved Salbutamol label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3236f82c-14e9-dfd4-e063-6294a90ac43d ; approved Sotalol label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9a36d95c-6e93-4e57-befe-b5274f359244 — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Decongestant + β2-agonist: additive sympathetic effects.
Pseudoephedrine is a sympathomimetic with alpha and beta activity (vasoconstriction and cardiac stimulation) and salbutamol a beta2-agonist; the adrenergic overlap adds up the cardiovascular effects — raised blood pressure (alpha), tachycardia and tremor (beta) — and salbutamol may also "produce significant hypokalaemia... with the potential to produce adverse cardiovascular effects" (salbutamol label). The combination is frequent in cold formulations in asthmatic patients and is particularly relevant in hypertensives, cardiac patients and hyperthyroidism. Prefer topical decongestants, use the lowest doses and monitor blood pressure, heart rate and potassium in at-risk patients.
Pseudoephedrine + salbutamol: alpha/beta-adrenergic overlap — raised blood pressure, tachycardia, tremor and hypokalaemia. Watch for cardiovascular symptoms.
Overlapping α/β-adrenergic effects raise blood pressure and heart rate.
Blood pressure and heart rhythm.
Hypertension, palpitations, tremor.
Use with caution in cardiovascular patients; watch for symptoms.
DailyMed (FDA) — approved Pseudoephedrine label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=78faa497-6743-b85b-e053-2a91aa0ae822 ; approved Salbutamol label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3236f82c-14e9-dfd4-e063-6294a90ac43d — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Epinephrine + β2-agonist: additive sympathetic effects and hypokalaemia.
Epinephrine activates alpha and beta receptors (beta1 and beta2) and salbutamol is a selective beta2-agonist; together, the additive beta stimulation increases tachycardia, tremor and intracellular potassium shift — the epinephrine label lists "hypokalaemia" among adverse reactions and the drugs that "potentiate the hypokalaemic effects of epinephrine", recommending watching for arrhythmias; salbutamol "may produce significant hypokalaemia in some patients... with the potential to produce adverse cardiovascular effects". The combination occurs mainly in emergency settings (anaphylaxis/acute asthma in a patient using beta2-agonists at home) and intensive care. Monitor cardiac rhythm and potassium, especially with repeated doses or in patients with coronary disease.
Epinephrine + salbutamol: beta-adrenergic overlap — additive tachycardia, tremor and potassium loss. Monitor cardiac rhythm and potassium.
Overlapping β-adrenergic effects increase tachycardia, tremor and potassium loss.
Potassium and heart rhythm.
Palpitations, tremor, hypokalaemia.
Monitor potassium and cardiovascular symptoms in at-risk patients.
DailyMed (FDA) — approved Epinephrine label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5726eeca-db88-ba8e-e063-6294a90a927d ; approved Salbutamol label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3236f82c-14e9-dfd4-e063-6294a90ac43d — additional reference: Prontuário Terapêutico do INFARMED (11th ed., 2012)
Caffeine may potentiate the effects of salbutamol (tremor, palpitations, tachycardia).
Limit caffeine intake in patients with adrenergic symptoms.
EMC-UK (MHRA) — approved Salbutamol SmPC: https://www.medicines.org.uk/emc/product/12983/smpc
β2-agonists may raise blood glucose, especially at high doses or in acute settings.
Monitor blood glucose in diabetic patients during treatment.
EMC-UK (MHRA) — approved Salbutamol SmPC: https://www.medicines.org.uk/emc/product/12983/smpc
Salbutamol is the most used bronchodilator in pregnancy and is considered safe at usual doses.
Can be used in all trimesters when indicated, under medical guidance.
Excreted in small amounts into breast milk; compatible with breastfeeding.
No specific additional contraception.
EMC-UK (MHRA) — approved Salbutamol SmPC: https://www.medicines.org.uk/emc/product/12983/smpc
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Selective short-acting beta-2 adrenergic agonist (SABA): relaxes bronchial smooth muscle of the whole airway tree, from the trachea to the terminal bronchioles, acting as a functional antagonist regardless of the spasmogen. Onset of action is ~6 minutes, with peak at 50–55 minutes and duration of ~3 hours (up to 6 hours in some patients).
Activation of beta-2 receptors on bronchial smooth muscle activates adenyl cyclase, increasing intracellular cAMP; cAMP activates protein kinase A, which inhibits myosin phosphorylation and lowers intracellular calcium, resulting in relaxation. Increased cAMP is also associated with inhibition of mast cell mediator release.
Salbutamol is rapidly and well absorbed orally, with an absolute bioavailability of ~44–50% for oral preparations; after inhalation, systemic absorption is rapid (low plasma levels). The MDI inhaler has an onset of action of ~6 minutes and peak effect at 50–55 minutes.
Salbutamol is extensively metabolised in the liver by conjugation (sulphation) to an inactive metabolite (salbutamol sulphate); elimination is mixed, renal and biliary. Oral bioavailability is ~50% (first-pass metabolism); after inhalation, the fraction reaching the circulation is small.
The elimination half-life of salbutamol is ~3.8–5 hours (mean ~5.7 hours for the drug and ~4.1 hours for the sulphate conjugate after an oral dose); after inhalation, the bronchodilator effect lasts ~3 hours (up to 6 hours in some patients).
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
